NIB/NOS! The Alpha 4050 was released in the late 80's as part of a 6 speed indexed group. It was a mid to upper level group, and directly aimed at defeating Shimano's SIS indexed groups. While Suntour eventually lost the war with Shimano, this was an excellent derailleur at a great price. Includes a unique piece, which bolts onto the rear of the derailleur in the case that the chain is too long to properly tension the derailleur in the smallest cog. When in place, this piece holds the cage in a slightly extended spot. Includes instructions manual.